1. Field of the Invention
This invention relates to Direct Access Storage Devices (DASD) and more specifically to the actuator of such a Direct Access Storage Device.
2. Description of Related Art
With the design of smaller Direct Access Storage Devices (DASDs) and implementation of industry standards, such as the Personal Computer Memory Card International Association (PCMCIA) standard, DASDs have become so small that available interior space is at a high premium. The size of the DASD and the corresponding sizes of the actuator contained within the DASD reduce the inherent structural strength of the components to the point that it is most difficult to manufacture the components and to maintain the necessary structural integrity. The difficulty arises with the requirement that the internal components both must have sufficient strength for operation and reliability, and be sufficiently small to fit within the size constraints imposed by the PCMCIA standard.
The material of the actuator coil holder, which extends between the support arms of the coil holder of the prior art actuators, could be removed to conserve space. However, the cantilever beam and the cantilever beam strength of the coil support arms then may not be sufficient to sustain drive forces and to preserve integrity while maintaining the bobbin shape and location relative to the actuator. This is particularly the case whenever the material selected for the coil holder is injection molded plastic.
The strength and integrity of the support arms are critical to the extremely-fine positioning of the actuator, and its associated load beam and slider with respect to the rotating recordable disks within the DASD.
In the coil support assembly of the prior art devices, the spanning member, which spans the gap between the support arms of the coil support assembly, provides stability to the support arms. This spanning member may not be eliminated if the overall size of the actuator coil holder is so reduced in size as to effect strength of the actuator assembly. The size of the coil is at least, in part, dictated by the drive forces required of the actuator motor.
The removal of the portion of the coil support assembly spanning the support arms of the coil support assembly to meet the criteria necessary for inclusion in the PCMCIA DASD design jeopardizes the reliability of the operation of the actuator. The drive forces, as exerted on portions of the coil, may cause flexure of the support arms of the coil assembly, thus destroying, or at least severely degrading, the position of the coil relative to the magnets of the actuator drive motor.
Degradation of the position of the magnetic coil relative to the magnet will commensurately degrade the position of the load beam and slider relative to the recordable disk surface. Thus, the disk drive will fail to yield the necessary recording density in terms of Tracks Per Inch (TPI).
If the size of the actuator coil holder is reduced to conform with the reduced dimensional requirements of the PCMCIA DASDs, the coil support assembly portion, which spans the support arms in the prior art actuator devices, occupies space which must be eliminated. On the other hand, the largest possible actuator coil size must be maintained to provide the necessary selection forces.
The actuator typically may be latched in an inactive position to prevent damage to the slider or the disk of the DASD whenever the actuator is not in use, or whenever the disk drive (DASD) is removed from the piece of equipment in which it may be installed for use.